Project Summary This application, submitted in response to RFA-MH-20-110, ?Secondary Data Analysis to Examine Long- Term and/or Potential Cross-Over Effects of Prevention Interventions: What are the Benefits for Preventing Mental Health Disorders?? proposes a 3-year project, aggregating data across three trials of the Family Check- Up (FCU), an empirically-supported prevention program designed to reduce behavior problems and substance use, to examine long-term collateral effects on depression and suicidal ideation / attempts. Depression is a highly prevalent disorder with long-term negative implications for healthy functioning across adolescence. Suicide-related behavior has escalated, particularly in early adolescence, often with tragic consequences. While a number of prevention programs targeting depression and suicide-risk have been developed, effect sizes are generally modest, many youth fail to respond to treatment, relapse rates are high, and evidence for long-term durability is limited (e.g., Birmaher et al., 2000; Beardslee et al., 2013; Sandler et al., 2014). There is, therefore, a pressing need for research that may identify novel and potentially modifiable developmental processes that may either amplify or attenuate risk for depression and suicide-related behavior across early development. It is also important to examine whether prevention programs modifying common risk-processes may achieve long-term collateral effects on depression and suicide risk, even though their original intention was to reduce risk of other types of problem behavior (e.g. disruptive behavior and substance use). Similarly, based on the variable responses to preventive interventions observed across trials, there is a critical need for research identifying heterogeneity in treatment outcomes, associated with either observed (e.g., gender or ethnicity) or latent (e.g., risk profiles) group membership. Such research is often hampered by the low base rate of suicidal behavior, in particular, in early adolescence, a serious limitation that may be addressed by synthesizing data across individual prevention trials. The proposed research involves novel secondary analyses, employing Integrated Data Analysis (IDA) procedures, to examine effects on depression and suicide-related behaviors in three large-scale prevention trials of the FCU prevention program, including 2322 families, with long-term follow-up data covering early childhood through early adulthood. The three trials include rich multimethod data on family and peer risk- processes, and overlapping assessment points in late childhood and early adolescence, a critical developmental span for depression and suicide-risk onset. Aggregating these datasets using IDA techniques will enhance statistical power, permitting rigorous examination of developmental pathways of risk, intervention factors (such as variation in treatment engagement) related to cross-over effects, mechanisms of such effects, and variability in outcomes across either observed or latent subgroups of youth.